So i Replaced the radiator in my 91 RS 305 TBI. When i did this I replaced both sensors, thermostat, upper hose, lower hose, overflow tank and radiator cap. I also changed my oil and filter, and flushed the block before putting in new coolant. So the other day I drove it to work it never got hot and it ran fine. Then on the way home i was about five miles into the drive and the temperature spiked and I mad it about another mile when the engine lost power. If I kept my foot on the gas the engine would stay running but once i took my foot off the pedal it stopped running. I rolled it out of the way and let it sit for about a minute and tried to start it again and it fired right up. This happened one more time on my drive home and the engine never cooled down. Soooo if anyone has any thoughts I'm mechanically incllined enough to do the work I just don't know where to start.

 

after changing all that stuff you may have had an air lock, did you check the coolant level? how hot did it get, you can sieze a motor up running it hot. any oil in the coolant.

 

I thought air lock to maybe but i filled the radiator up then ran it with the cap off till it got warm so that the thermostat opened and filled it the rest of the way and filled the overflow to the hot line. The way to work it ran at normal operating temp. Then on the way home it topped out the temp gauge. As for oil in the coolant it doesn't look like it the anti-freeze is still green.

 

lol, i meant to say coolant in the oil. so you werent low on coolant in the radiator after getting home and lettting it cool off?

 

What was the reason for replacing the radiator?

 

I didn't check to see if there is coolant in the oil so i will check that out. I replaced it just to update it, it still had the original radiator in it.

 

check the wiring for the sensors. if they ground out, the gauge will spike. im not sure if the ecm on the tbi engine will derate power when the engine is too hot, i know some vehicles it will. does it have electric fans or a clutch fan?